IP Routing


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IP Routing

  1. 1. IP Routing Chapter 6
  2. 2. Chapter Objectives  Explain Protocols  Explain Routing Metrics  Discuss Routing Mechanisms  Explain Routing Algorithms  Set up routingChapter 6 2
  3. 3. Recall The router configuration files are located in:  RAM  NVRAM  TFTP Server Protocol that gives the information about locally attached and remote devices in the network is termed as Cisco Discovery Protocol (CDP) CDP global parameters include:  CDP timer  CDP holdtimeChapter 6 3
  4. 4. Goals of Routing Routing process ensures that appropriate packets are routed from the source to the destination Goals of routing include:  Stability  Provides with a robust network  Dynamic update of the network paths  Information is safe while transmittingChapter 6 4
  5. 5. IP Routing with One RouterChapter 6 5
  6. 6. IP Routing with Three RoutersChapter 6 6
  7. 7. Process of Routing Packets within aRouterChapter 6 7
  8. 8. Routing Metrics Routing metrics are values that allow the routers decide the best route for the data packet Different routing metrics include:  Hops  Bandwidth  Load  Cost  ReliabilityChapter 6 8
  9. 9. Dynamic Routing The phenomena in which the routing protocols are assigned the job of finding the path to route the packets and update the routing tables Two types of dynamic routing protocols include:  Interior routing protocols  Exterior routing protocolsChapter 6 9
  10. 10. Administrative Distance An integer assigned to every routing protocol, which determines the reliability of the routing protocol is termed as administrative distance (AD) The integer is in the range of 0 to 255 Lower the AD, more reliable is the routing information provided by the routing protocolChapter 6 10
  11. 11. AD of Routing Protocols Routed Source Default ADConnected Interface 0Static Route 1Enhanced Interior Gateway Routing Protocol 90(EIGRP)Interior Gateway Routing Protocol (IGRP) 100Open Shortest Path First (OSPF) 110Routing Information Protocol (RIP) 120External EIGRP 170Unknown 255 (This route will never be used)Chapter 6 11
  12. 12. Interior Routing Protocols The protocols used to route the packets inside an autonomous system, are termed as Interior Routing protocols Interior routing protocols include:  Routing Information Protocol (RIP)  Open Shortest Path First (OSPF)  Interior Gateway Routing Protocol (IGRP)  Enhanced Interior Gateway Routing Protocol (EIGRP)  Intermediate System to Intermediate System (IS – IS)Chapter 6 12
  13. 13. Exterior Routing Protocols The routing protocols that communicate between the two or more Autonomous Systems (AS) are termed as Exterior routing protocols Exterior Routing Protocols include:  Exterior Gateway Protocols (EGP)  Border Gateway Protocol (BGP)Chapter 6 13
  14. 14. Routing Tables The routing tables then decide the best path to the route the packet, which also includes the next hop address Information contained in the routing table include:  Destination  Next hop address  Outgoing interface  Routing ProtocolsChapter 6 14
  15. 15. Static Routing The phenomena of adding routes manually to the routing table, is termed as static routing This is feasible in small networks, but not in large networksChapter 6 15
  16. 16. Routing Information Protocol (RIP) RIP allows routers to exchange their routing tables at a predefined interval Characteristics of RIP include:  Uses hop count metric  Supports 15 hop-count limit  Supports six equal-cost pathsChapter 6 16
  17. 17. Distance Vector concept The routers connected to the neighboring networks update the list of networks and the hop counts in the routing table The connected routers update the routing table with the network information The routers connected to the distant networks construct a new routing table The network information of the connected routers combined with the new routing table entries is passed to all the neighboring routing tablesChapter 6 17
  18. 18. RIP Timers RIP timers are used to keep a track of the various routes connected The different RIP timers include:  Route update timer  Route invalid timer  Holddown timer  Route Flush timerChapter 6 18
  19. 19. Enhancements in RIPv2 RIPv2 was created to overcome the drawbacks of RIPv1 RIPv2 enhancements include:  Multicasting  Triggered updates  Classless protocol  AuthenticationChapter 6 19
  20. 20. Case StudyThe Hyderabad branch of the Blue Diamond SteelCompany has 10 routers connected in the network.Initially, the network administrator had configured thenetwork to use static routes to route the packetscontaining the data and to communicate between thenetworks. Now the company has decided employmore than 100 employees for their operations inSoftware Management, Human Resource, Detailing,Business Development and Sales. This requires thecompany to add five more networks to the existingones.Chapter 6 20
  21. 21. Problem The network administrator has to manually add routes to all the networks connected and then send the packetsChapter 6 21
  22. 22. Solution The network administrator decided to use RIP, which is a dynamic routing protocol. It can add the routes to the network automatically and uses hop count as its metric to route the packets and can be used to connect small networksChapter 6 22
  23. 23. Summary - I Routing occurs at the network layer of the OSI model Protocols are a set of rules that define data transfer The routing protocols can be classified based on their routing abilities as:  Interior Routing Protocols  Exterior Routing ProtocolsChapter 6 23
  24. 24. Summary - II Interior Routing protocols can be classified as:  Routing Information Protocol (RIP)  Open Shortest Path First (OSPF)  Interior Gateway Routing Protocol (IGRP)  Enhanced Intermediate System to Intermediate System (EIGRP)  Intermediate System to Intermediate System Exterior Routing protocols can be classified as:  Exterior Gateway Protocol (EGP)  Border Gateway Protocol (BGP)Chapter 6 24
  25. 25. Summary - III Routing metrics are cost values that enable routers decide the best route for the data packet When a router forwards a data packet to a network segment, it is counted as a single hop Bandwidth measures the amount of data that can travel over the network segment in a fixed amount of time Delay specifies the amount of time that a router takes to process and transfer a data packet to the next device on the network The delay is represented with a µ symbolChapter 6 25
  26. 26. Summary - IV Load refers to the amount of traffic on a particular link relative to the total capacity of the link The load value 255 indicates 100% traffic congestion Direct interfaces consist of routes that are local to the router Routed protocols consist of protocols that define routing and addressing Routing protocols are a set of rules that are implemented on a router to determine the best path to route the packetsChapter 6 26
  27. 27. Summary - V Routing protocols can be classified into Interior Routing Protocols and Exterior Routing Protocols Every router has a routing table based on which the data packets are forwarded to the destinations Static routes are the routes that the administrator manually enters in the routing table Static routes are used in temporary connections such as dial-up networks The router automatically collects and stores dynamic routes in the routing tableChapter 6 27
  28. 28. Summary - VI Enhancements in RIPv2 include:  Supports multicast updates against broadcast updates  Uses triggered updates to share its routing information with the neighbors, when a change occurs  Supports Variable-Length Subnet Masking (VSLM)  Allows you to select the routers you want to participate in RIPv2Chapter 6 28